Shares of Adeza Biomedical ( ADZA) were among health care stocks' winners Monday, rising more than 50% on news of a merger. Cytyc ( CYTC) agreed to acquire the maker of products for women's health for $24 a share, or $452 million. The merger is expected to close by the end of March. Shares of Adeza were up $8.25, or 53%, to $23.78 in recent trading. Cytyc shares were up 59 cents, or 2%, at $30.14. Onyx Pharmaceuticals ( ONXX) was surging 91% Monday after the company said a trial of the liver cancer drug Nexavar met its primary endpoint . Onyx and partner Bayer ( BAY) ended the phase III trial early on recommendation of an independent data-monitoring committee and gave all patients in the study access to Nexavar. Onyx shares were up $11.14 at $23.40 in recent trading. Bristol-Myers Squibb ( BMY) dropped lower on reports that merger talks with Sanofi-Aventis ( SNY) have come to an end. Bristol shares were recently down $1.05, or 3.7%, at $27.47, while Sanofi was higher by 24 cents, or 0.6%, at $44.02. Medifast ( MED) climbed higher on an 83% year-over-year increase in full-year revenue. The weight-loss company reported unaudited revenue of $73.5 million, up from $40.1 million in 2005 and higher than its previous guidance of $70 million to $72 million. Analysts are looking for $73.3 million in revenue, according to Thomson First Call. Shares were recently higher by $1.37, or 17.6%, at $9.14.